Chronic pain is an important public health issue, affecting as many as 25% of adolescents. Over half of these adolescents report sleep disturbances, such as insomnia, that have the potential to diminish normal daily function, disturb mood, and hinder quality of life. Treatments for sleep problems in pediatric pain populations have not been developed due to lack of knowledge of the specific nature and diagnostic characteristics of these sleep-wake disturbances. The long-term goal of this research program is to develop effective treatments that reduce both chronic pain and sleep disturbances in children and adolescents. The specific aims of this application are to 1) characterize the nature and impact of sleep-wake disturbances experienced by adolescents with chronic pain using subjective survey measures and actigraphy, 2) identify behavioral and psychological factors associated with the pain and sleep relationship, and 3) determine trajectories in sleep-wake disturbances over 12 months. This longitudinal study is composed of three data waves. Time 1 is a cross-sectional comparison of sleep patterns and behaviors, and psychological factors associated with sleep in 240 adolescents, ages 12 to 17 years, (n=60 adolescents with chronic nonmalignant pain, n=60 adolescents with a primary behavioral sleep disorder, n=60 adolescents with major depressive disorder, and n=60 otherwise healthy adolescent peers). Subjective and objective assessment of sleep will be conducted. Ambulatory actigraphy recordings will be completed over 10 days and adolescents will complete subjective sleep measures and an electronic sleep and behavior diary. Behavioral assessment will include a psychiatric screening interview, symptom inventories, and a measure of pre-sleep arousal. Time 2 and Time 3 data waves will occur at 6 and 12 months post study-entry. Repeated assessments of sleep, pain, and behavioral factors will be conducted to examine predictors of sleep disturbances over time. In addition, daily assessment methodology will be used to test a mediation model of the role of depressed mood in the relationship between pain and sleep. Knowledge gained by the proposed studies is expected to positively affect the health of children and adolescents because it will allow the development of new interventions that are designed to decrease pain and sleep disturbances. These advances may ultimately improve the adaptive functioning and quality of life of the substantial population of adolescents affected by chronic pain, and lead to a better understanding of how to prevent the development of disabling, costly pain and sleep problems in adulthood.